1. Field of the Invention
The disclosed embodiments of the present invention relate to sensing pattern design, and more particularly, to an electrode unit with a perimeter-lengthened touch-sensing pattern on a touch-sensing element located at fringes of a touch panel.
2. Description of the Prior Art
Regarding a single-layered capacitive touch panel, a touch-sensing element on a touch panel is usually implemented using longitudinal electrodes and transverse electrodes with transparent conductive materials (e.g., indium tin oxide (ITO)). When a finger touches a longitudinal electrode and a transverse electrode, an inductive capacitance between the touched longitudinal electrode and transverse electrode alters responsively. The difference of the inductive capacitance before and after the touch can then be used to calculate where the contact is.
Please refer to FIG. 1, which is a schematic diagram illustrating an example of a sensing pattern of electrodes on a conventional touch panel TP. The touch panel TP includes a plurality of touch-sensing elements TU, where each of the touch-sensing elements TU has an electrode unit 100 thereon, and the electrode unit 100 includes at least a first transverse electrode 110 and a second longitudinal electrode 120. As shown in FIG. 1, the touch-sensing elements TU are staggered as a rectangular pattern, the first electrode 110 on the same row are series-connected as a sensing trace, and the second electrode 120 on the same column are series-connected as a sensing trace. In this way, the touch panel TP would have a plurality of transverse sensing traces T1-TN and a plurality of longitudinal sensing traces S1-SM. In addition, the electrode unit 100 also has separation units constituted by insulation material and disposed on an intersection of the corresponding first electrode 110 and second electrode 120, such that the sensing traces T1-TN and sensing traces S1-SM would not be electrically connected.
However, since an area being able to induct the inductive capacitance between two adjacent electrodes (i.e., the first electrode 110 and the second electrode 120) on the touch-sensing element TU located on fringes of the touch panel TP is smaller than an area being able to induct the inductive capacitance between two adjacent electrodes (i.e., the first electrode 110 and the second electrode 120) on the touch-sensing element TU located in the middle of the touch panel TP, when the finger enters the touch panel TP from the fringe, the inductive capacitance sensed by the electrodes on the fringes is smaller than the inductive capacitance sensed by the electrodes in an effective sensing area, which is prone to misjudgment.
Therefore, there is a need to enhance the inductive capacitance sensed by the electrodes of the touch-sensing element located on the fringes of the touch panel, in order to decrease the likelihood of faulty calculation of contact on the fringes of the touch panel.